Fitted sheets, which are also referred to as “bottom” sheets, are conventionally formed of fabric and are used to cover and protect a mattress. A fitted sheet typically comprises a top panel, two side panels and two end panels, and in general, the top panel is disposed over the top surface of the mattress, while each of the four side and end panels extends from the top panel and covers a sidewall or endwall, and at least a portion of the bottom surface, of the mattress. Further, each side panel is usually joined to each adjacent end panel at their respective edges by seams, in a manner to form corners adapted to conform to the shape of the mattress. A fitted sheet may also include some arrangement for securing the fitted sheet to the mattress and/or for keeping the fitted sheet in place on the mattress.
Nevertheless, fitted sheets often become displaced during use, which causes a disheveled look, and which may also cause discomfort to the user. Moreover, although nowadays mattresses are available commercially in several popular sizes, having width and length dimensions that are standardized within the bedding industry (e.g., “king,” “queen,” “full,” “twin,” etc.), in fact the dimensions of mattresses do vary from manufacturer to manufacturer, and even among the various mattress lines or models of the same manufacturer, particularly with respect to the thickness of the mattress. In other words, there is no “standard” mattress thickness dimension; rather, the thickness of particular mattresses may vary, depending on a number of factors such as the type or manufacturer of the bed, and the preferences of individual users. Therefore, fitted sheets designed for use on a mattress of a particular size, such as a “queen” size mattress, may not fit snugly on all mattresses of that size. Moreover, over time, an individual mattress may tend to change its size and shape, due to a variety of factors such as age and/or excessive use and/or environmental factors.
Accordingly, there is a need for a fitted sheet capable of remaining in place during use, and which, at the same time, can accommodate and fit snugly on mattresses of varying thicknesses, and can also adapt to any changes in mattress size and shape, while continuing to appear smooth and neat, at least along the top surface and sidewalls of the mattress. Although efforts have been made in the prior art to provide fitted sheets that can overcome these problems, such as those described in U.S. Pat. Nos. 5,287,574, 7,398,570 and 8,171,581, those efforts have not been completely satisfactory.
Most of these prior art solutions involve blending stretchable and non-stretchable portions into the fabric that forms the side panels of the sheet, such that the stretchable fabric portions are located at or near the corners. However, this solution may lead to undesirable consequences, such as differential shrinkage of the sheet after laundering, as well as a “mottled” appearance due to slight differences in the coloration of portions of the sheet, either initially or after laundering. These undesirable consequences are a direct result of blending stretchable and non-stretchable yarns into portions of the fabric, as these portions are assembled of yarn fibers having different characteristics. Since such blending is common to all of these prior art solutions, it is a fundamental flaw of the prior art.
It is therefore the principal object of the present invention to provide improved fitted bed sheets which are capable of remaining in place during use, which can fit the contours mattresses of varying thicknesses, and which, at the same time, do not exhibit the undesirable effects caused by the incorporation into the side panels of the sheet of both stretchable and non-stretchable portions of fabric.